Invalid JSON files in IPF_ETC/workflows/glue2 will cause ipfinfo step to fail

[ericblau]

The ipfinfo step needs to have better error handling; currently if there is an unparsable json file in the workflows directories, it causes the step to fail, which will cause the workflow to fail.

Example where a zero-length .json file is in the directory:

Process IPFWorkflowsStep-121:
Traceback (most recent call last):
File "/usr/lib64/python3.6/multiprocessing/process.py", line 258, in _bootstrap
self.run()
File "/usr/lib/python3.6/site-packages/ipf/ipfinfo.py", line 185, in run
self._output(IPFWorkflows(ipf_version, self._run()))
File "/usr/lib/python3.6/site-packages/ipf/ipfinfo.py", line 204, in _run
d = json.load(json_data)
File "/usr/lib64/python3.6/json/init.py", line 299, in load
parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
File "/usr/lib64/python3.6/json/init.py", line 354, in loads
return _default_decoder.decode(s)
File "/usr/lib64/python3.6/json/decoder.py", line 339, in decode
obj, end = self.raw_decode(s, idx=_w(s, 0).end())
File "/usr/lib64/python3.6/json/decoder.py", line 357, in raw_decode
raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)